FR2833694A1 - PYROTECHNIC SEPARATOR AND SEPARATION DEVICE PROVIDED WITH SUCH A SEPARATOR - Google Patents

Abstract

It comprises first (51) and second (52) assembly flanks of parts (1; 2a, 2b), which must separate in a predetermined direction. The flanks enclose between them a pyrotechnic cord (7, 8, 9) crushed, of the first (141) and second (142) weakening zones running on said first (51) and second (52) flanks respectively, parallel and in the vicinity of the bead (7, 8, 9), and means (11) for selectively activating said bead (7, 8, 9) and thus causing the rupture of said flanks (51, 52) along said weakened zones (141, 142). According to the invention, said zones (141, 142) together define a breakage envelope surface (S) inclined on said direction, said inclination being oriented so as to allow mutual release of the two parts (1; 2a, 2b) in said direction without mechanical interference, to the activation of said bead. Application to the ejection of the fairing of a space launcher.

Description

The present invention relates to a pyrotechnic separator con cu

  to be installed along a joining line of two mechanical parts temporarily assembled and designed to separate in a predetermined direction, and, more particularly, to such a separator comprising first and second flanks for assembling said parts, enclosing between them a crushed pyrotechnic cord running along said junction line, the first and second weakening zones running on said first and second flanks respectively, parallel to and in the vicinity of said cord, and means for selectively activating said cord and thereby causing breakage of said flanks at along said

areas of weakness.

  Such a separator is well known, see for example the patent of the United States of America N 3,698,281 in the name of BranUt, and it finds particular application in the aerospace industry, where it is used in particular to ensure the

  separation of space launch vehicle elements.

  As an illustrative and nonlimiting example, there is shown in Figure 1 of the accompanying drawing a first mechanical part 1, in the form of a ferrule, cylindrical of revolution, constituting the upper part of the casing of such a launcher, this first part being surmounted by an ovoid cap made up of second and third parts 2a, 2b in the form of half-caps, this cap having the function of protecting a payload (not shown) such as an artificial satellite for example, during the crossing of the

dense layers of 1 T atmosphere.

  Approaching the nominal orbit on which the satellite is to be installed, it is naturally advisable to eject laterally the two half-tails 2a, 2b in the direction of the arrows f1 and f2 in opposite directions, together defining a direction D. To allow this ejection, the half-caps 2a, 2b and the ferrule 1 are conventionally assembled, as described in the patent of United States of America N 3,453,960 in the name of Qualls, along first and second junction lines respectively, equipped first and second

separators 3 and 4 respectively.

  The first separator, pyrotechnic, runs along a circular junction line on which the

  two semi-circular half-bases of the half-caps 2a and 2b.

  lo This is why this first separator can also be

  consisting, as shown, of two semi-separators

  circular. The second separator 4 runs along a section of

  the cap by a plane passing through the X axis of the launcher.

  Thus the first and second separators 3 and 4 are installed in planes P1 and P2 respectively, the plane P1 being perpendicular to the axis X of the launcher while the plane P2 passes through this axis, between the two half-caps 2a and 2b symmetrical with respect to this plane, itself

  perpendicular to the direction D in which the half

  caps separate from each other to release the load

useful carried by the launcher.

  The separator 4 is of a known type, ensuring the lateral separation of the two half-caps 2a, 2b according to the arrows f1, f2 respectively. It can be pyrotechnic,

  like the first or, alternatively, spring loaded.

  The separator 3 is commonly of one or the other of two known types, called "symmetrical" and "asymmetrical" respectively. An example of a "symmetrical" separator is described in the above-mentioned Brandt patent, while an example of an "asymmetrical" separator is shown in Figures 3 and 4 of the Qualls patent, also mentioned above. Whether it is of the "symmetrical" or of the "asymmetrical" type, a pyrotechnic separator conventionally comprises a pyrotechnic cord comprising an expandable tube made up of a metal envelope of oblong or "crushed" straight section, the tobe being filled with a charge explosive. The tube is placed between two sides, plates, flanges or shoulders,

  integral with the two parts assembled by the separator.

  When the separator is asymmetrical, one of these sides, plates, flanges, etc. is hollowed out with a weakening line, a groove for example, at the level of the expandable tube. When the separator is symmetrical, the two sides are hollowed out with such a weakening line, which are then arranged symmetrically

  with respect to a median plane of the separator.

  Upon ignition of the explosive charge contained in the tube, the latter tends to take a circular shape and then pushes back the walls of the sides between which it is pinched, which causes the rupture of the weakening line or lines, and therefore the physical separation of the parts

previously assembled.

  An asymmetrical separator offers the advantage, when it is used to constitute the separator 3, of contributing to the lateral displacement of the two half-caps, by the very fact of its asymmetry. On the other hand, the explosion of the charge contained in the pyrotechnic cord applies high level shocks to the assembled structures, which propagate in these structures and can then damage the equipment.

  mounted thereon (including the launcher payload).

  A symmetrical separator offers, over an asymmetrical separator, the advantage of applying to structures shocks of lower levels. On the other hand, because of its symmetrical geometry, it does not contribute to the lateral separation of the

  two half-caps, which it can even generate.

  The object of the present invention is therefore to produce a pyrotechnic separator capable of constituting, in particular, the separator 3 of the cap shown in FIG. 1, this separator combining the advantages of the separators of the two types examined above, without having the disadvantages thereof. . The present invention also aims to produce a pyrotechnic separation device for at least first, second and third temporarily assembled mechanical parts, comprising the following separator

the invention.

  These and other objects of the invention are achieved

  which will appear on reading the description which will

  follow, with a pyrotechnic separator designed to be installed along a junction line of two mechanical parts temporarily assembled and designed to separate in a predetermined direction, this separator comprising first and second flanks for assembling said parts enclosing them a crushed pyrotechnic cord running along said junction line, first and second weakening zones running on said first and second flanks respectively, parallel to and in the vicinity of said cord, and means for selectively activating said cord and thereby causing breakage said flanks along said weakening zones, this separator being remarkable in that said zones together define a fracture envelope surface inclined at any point on said predetermined direction, said inclination being oriented so as to allow mutual clearance of the two parts according to said predetermined direction, without mechanical interference,

upon activation of said cord.

  The separator according to the invention makes it possible to constitute a pyrotechnic separation device for at least first, second and third mechanical parts temporarily assembled along first and second connecting lines equipped with first and second pyrotechnic separators running between the first part and said parts second and third parts, and between said second and third parts, respectively, said first and second junction lines developing in first and second planes perpendicular to each other and said second and third parts being symmetrical with respect to the second plane, this device being remarkable in that said first pyrotechnic separator is as T stated above and in that said second pyrotechnic separator is equipped with activation means triggered in synchronism with those of the first pyrotechnic separator, to cooperate with the spacing said second and third pieces in said direction

  predetermined, perpendicular to said second plane.

  Other features of the present invention

  will appear on reading the description which follows and

  on examination of the appended drawing in which: - Figure 1 is a schematic perspective view of the separation device according to the invention, applied to parts constituting the cap of a space launcher, this device being partially

  described in the preamble to this description,

  - Figures 2 and 3 show cross-sectional views of the separator according to the invention, respectively before and after activation of the explosive charge contained in the pyrotechnic cord of this separator, and, - Figure 4 is a view, with partial section , from

  means for activating said charge.

  We refer to Figures 2 and the accompanying drawing which show a pyrotechnic separator designed, in particular, to constitute the separator 3 of Figure 1, this application being given by way of illustrative example and

nonlimiting only.

  In this example, the separator 3 comprises two semi-circular halves placed end to end. The section views of this separator shown in Figures 2 and 3 are taken in the section plane P3 of Figure 1, where the separator establishes a frangible connection between the part 1 in the form of a ferrule and the part 2b in the form of a half cap. We will only describe below the part of the separator 3 placed between the shell 1 and the half-cap 2b, the other part of this separator being identical. As shown in Figures 2 and 3, the separator 3 comprises first and second flanks 51, 52 extending from the part 1 in a cross section in the form of a yoke, an edge portion of the cap 2b inserted between these two flanks delimit an annular chamber in which is housed a pyrotechnic cord with an oblong straight section, or "flattened", clamped between the sides 51, 52. The ferrule 1 and the half-cap 2b are assembled by a series of bolts such as that referenced 6 which crosses the ferrule 1 and the

flanks 51, 52.

  The pyrotechnic cord conventionally comprises an expandable metal tube 7 internally lined with a cord of pyrotechnic material 8 centered in the tube by a

setting product 9, for example.

  Each of the two cords (7, 8, 9) forming part of the separator 3 is equipped, at each of its two ends leaving the cap 2a, 2b by windows 10a, 10b visible in FIG. 1, with activation means 11

  classics shown in more detail in Figure 4.

  In this figure it appears that the tube 7 of the cord is held, at its exit from the cover, by a ring 12 traversed by the tube 7 and fixed on the ferrule 1 by means of a

screw 13.

  In Figure 2 it appears that the separator according to the invention comprises two weakening zones 14l, 142, defined by notches or grooves (15a, 15b) and (16a, 16b) respectively, dug in the two opposite faces

  flanks 51, 52 respectively, at the base of these flanks.

  The thickness of the weakening zones and the geometry of the separator in the vicinity of the expandable tube 7 are defined so as to minimize the pyrotechnic shock when igniting the pyrotechnic cord (7, 8, 9) as well as the shock due to relaxation separate rooms. The optimization carried out relates to the arrangement of the weakening zones. According to the present invention, these two weakening zones are arranged asymmetrically with respect to the median plane P4 of the separator (see FIG. 2) so as to define, after their rupture, an "envelope" surface of fracture S whose trace, in the plane of Figure 3, is inclined to the direction D in which the two half-caps 2a, 2b must deviate from one

the other (see Figure 1).

  This trace is defined by a straight line

  appreciably by the mediums of the weakened zones.

  As shown in zone 14, the break in these zones is not necessarily parallel to the trace of surface S. In FIG. 3, which represents the separator after the ignition of the pyrotechnic cord (7, 8, 9), it appears that the trace of the surface S in the plane of the figure is inclined so as to allow the lateral sliding of the half-cap 2b, for example, in the direction of the arrow f2, without risk of catching or other mechanical interference with the ferrule 1. I1 is the same with the other half-cap 2a. To do this, the surface S takes a frustoconical shape (when the ferrule 1 is cylindrical of revolution), the top of the cone tangent to this shape being on the axis X, on the side of the cap (2a, 2b), by compared to plan P1. The weakening zone 141, the radius of which is smaller than that of the zone 142, is then above the zone 142 when it is marked with respect to the axis X, as it is

oriented on figure 1.

  It also appears in FIGS. 2 and 3 that the surface S tangents the pyrotechnic cord (7, 8, 9) both before the firing of this cord, and after this firing (see FIG. 3). We will explain the interest of this

  provision in the remainder of this description,

  dedicated to the operation of the separator and the device

  separator according to the invention.

  Activation of the pyrotechnic separator according to the invention takes place as seen above, using means 11 mounted at the ends of the cord (7, 8, 9), means commonly called "detonators" or " pyrotechnic transmission lines ". An initiation center (not shown) coordinates and synchronizes the activations of the detonators or of the transmission lines associated with the various cords forming part of the separators 3 and 4 of the device represented in FIG. 1, so as to ensure separation and ejection half-jaws 2a, 2b according to the arrows f

and f2 respectively.

  The impulse required for this ejection is obtained by firing the separator 4. In fact, the firing of the separator 3 does not develop a sufficient radial force

to ensure this election.

  When the or the cords (7, 8, 9) of the separator 3 are ignited, the detonation of the pyrotechnic charge causes the expandable tube 7 to swell, which then transmits the shock wave produced by the detonation to the sides 51, 52 on which it is based. This shock wave causes shear stresses such as these zones to break in the weakening zones 141, 142 causing the breaking surface S. to appear. The swelling of the tube 7 makes it lose its oblong shape and gives it a shape substantially elliptical (as shown in FIG. 3) which causes the tube to block against the opposite faces of the sides 5, 52. The tobe 7 then remains integral with the ejected half-cap 2a or 2b, which avoids any dangerous dispersion of its components in

the environment of the launcher.

  After swelling, the tube 7 also remains tangent to the fracture surface S (see FIG. 3), which allows the half-cap with which it is attached to move freely away from the launcher, thanks to the impulse provided by the separator 4, and this without any risk of mechanical catching on the surface facing the shell 1, in accordance with one of the aims of the

present invention.

  A suitable choice of the half-angle at the top of the frustoconical breaking surface S., for example between 10 and

    completely eliminates this risk of snagging.

  As the overall geometry of the separator according to the invention remains close to that of a so-called "symmetrical" separator, the advantage of the latter is further preserved, namely the low level of shock applied to the adjoining structure during the setting up. separator fire, especially in the frequency band from 500 Hz to 10 000 Hz approximately. Of course, the invention is not limited to the embodiment described and shown which has been given only by way of example. Thus, the separator according to the invention is not limited to its use in a device of the type of that represented in FIG. 1 of the

attached drawing.

  It can find application, on the contrary, whenever it is necessary, during the pyrotechnic separation of two parts, to eliminate any risk of mechanical interference between these two parts while minimizing the level of shock

  pyrotechnic transmitted to the assembled parts.

Claims (5)

  1. Pyrotechnic separator designed to be installed along a junction line of two mechanical parts (1; 2a, 2b) temporarily assembled and designed to separate in a predetermined direction (D), comprising first (51) and second (52) ) joining flanks of said parts (1; 2a, 2b) enclosing between them a pyrotechnic cord (7, 8, 9) crushed running along said junction line, first (141) and second (142) zones of. current weakening on the first (51) and second (52) sides respectively, parallel to and in the vicinity of said cord (7, 8, 9), and means (11) for selectively activating said cord (7, 8, 9) and causing thus the rupture of said flanks (51, 52) along said weakening zones (141, 142), characterized in that said zones (141, 142) together define a fracture envelope surface (S) inclined at all points on said predetermined direction (D), said inclination being oriented so as to allow mutual clearance of the two parts (1; 2a, 2b) in said direction (D) without   mechanical interference upon activation of said cord.   2. Separator according to claim 1, characterized in that said pyrotechnic cord (7, 8, 9) is. after activation, retained between said sides (51, 52),   entirely on the same side of said breaking surface (S).   3. Device for pyrotechnic separation of at least first (1), second (2a) and third (2b) mechanical parts temporarily assembled along first and second connecting lines equipped with first (3) and second (4) current separators between the first part (1) and the second (2a) and third (2b) parts, and between said second (2a) and third (2b) parts, respectively, said first and second junction lines developing in first (P1 ) and second (P2) planes perpendicular to each other and the second (2a) and third (2b) parts being symmetrical with respect to the second plane (P2), characterized in that said first separator (3) conforms to any one claims 1 and 2 and in that the edit second separator (4) cooperates with the first separator (3), at the spacing of said second (2a) and third (2b) parts in said predetermined direction (D),perpendicular to said second plan (P2).   4. Device according to claim 3, characterized in that said first part (1) forms part of the envelope of a space launcher, and in that lesUits second (2a) and third (2b) parts are half-hairstyles of such a launcher.   5. Device according to claim 4, characterized in that at least one end of said cord (7, 8, 9) is equipped with said activation means (11) and in that said end passes through said casing of said launcher, and a ring (12) fixed on this envelope for